/Engine/Source/Editor/GraphEditor/Public/SGraphNode.h
the node under the mouse (either this node or one of its children)
virtual [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SGraphNode](API\Editor\GraphEditor\SGraphNode) > GetNodeUnderMouse ( const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & MouseEvent )